Equilibrium Adsorption Measurements of Pure Nitrogen, Carbon Dioxide, and Methane on a Carbon Molecular Sieve at Cryogenic Temperatures and High Pressures†

2009 ◽  
Vol 54 (9) ◽  
pp. 2701-2707 ◽  
Author(s):  
G. Watson ◽  
E. F. May ◽  
B. F. Graham ◽  
M. A. Trebble ◽  
R. D. Trengove ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Molecular Sieve ◽  
High Pressures ◽  
Equilibrium Adsorption ◽  
Cryogenic Temperatures ◽  
Carbon Molecular Sieve ◽  
Pure Nitrogen

Kinetic separation of carbon dioxide from hydrocarbons using carbon molecular sieve

1993 ◽  
Vol 7 (4) ◽  
pp. 259-263 ◽  
Author(s):  
Akhilesh Kapoor ◽  
Krish R. Krishnamurthy ◽  
Arthur Shirley
Keyword(s):  
Carbon Dioxide ◽  
Molecular Sieve ◽  
Carbon Molecular Sieve ◽  
Kinetic Separation

Diffusion of Methane and Carbon Dioxide in Carbon Molecular Sieve Membranes by Multinuclear Pulsed Field Gradient NMR

Langmuir ◽  
2012 ◽  
Vol 28 (27) ◽  
pp. 10296-10303 ◽  
Author(s):  
Robert Mueller ◽  
Rohit Kanungo ◽  
Mayumi Kiyono-Shimobe ◽  
William J. Koros ◽  
Sergey Vasenkov
Keyword(s):  
Carbon Dioxide ◽  
Field Gradient ◽  
Molecular Sieve ◽  
Carbon Molecular Sieve ◽  
Pulsed Field Gradient Nmr ◽  
Pulsed Field

scholarly journals Water Adsorption Effect on Carbon Molecular Sieve Membranes in H2-CH4 Mixture at High Pressure

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3577
Author(s):  
Maria L. V. Nordio ◽  
José A. Medrano ◽  
Martin van Sint Annaland ◽  
David Alfredo Pacheco Tanaka ◽  
Margot Llosa Tanco ◽  
...  
Keyword(s):  
High Pressure ◽  
Molecular Sieve ◽  
Water Adsorption ◽  
High Pressures ◽  
Operating Conditions ◽  
Raw Material ◽  
Carbon Molecular Sieve ◽  
Adsorption Effect ◽  
Palladium Membranes ◽  
Different Temperatures

Carbon molecular sieve membranes (CMSMs) are emerging as promising solution to overcome the drawbacks of Pd-based membranes for H2 separation since (i) they are relatively easy to manufacture; (ii) they have low production and raw material costs; (iii) and they can work at conditions where polymeric and palladium membranes are not stable. In this work CMSMs have been investigated in pure gas and gas mixture tests for a proper understanding of the permeation mechanism, selectivity and purity towards hydrogen. No mass transfer limitations have been observed with these membranes, which represents an important advantage compared to Pd-Ag membranes, which suffer from concentration polarization especially at high pressure and low hydrogen concentrations. H2, CH4, CO2 and N2 permeation at high pressures and different temperatures in presence of dry and humidified stream (from ambient and water vapour) have been carried out to investigate the effect of the presence of water in the feed stream. Diffusion is the main mechanism observed for hydrogen, while methane, nitrogen and especially carbon dioxide permeate through adsorption-diffusion at low temperatures and high pressures. Finally, H2 permeation from H2-CH4 mixtures in presence of water has been compared at different temperatures and pressure, which demonstrates that water adsorption is an essential parameter to improve the performance of carbon molecular sieve membranes, especially when working at high temperature. Indeed, a hydrogen purity of 98.95% from 10% H2—90% CH4 was achieved. The main aim of this work is to understand the permeation mechanisms of CMSMs in different operating conditions and find the best conditions to optimize the separation of hydrogen.

scholarly journals Pore Structure Alteration of a Carbon Molecular Sieve for the Separation of Hydrogen Sulfide from Methane by Adsorption

1993 ◽  
Vol 10 (1-4) ◽  
pp. 193-201 ◽  
Author(s):  
Z.J. Pan ◽  
S.G. Chen ◽  
J. Tang ◽  
R.T. Yang
Keyword(s):  
Natural Gas ◽  
Pore Structure ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Carbon Deposition ◽  
Important Variable ◽  
Equilibrium Adsorption ◽  
Carbon Molecular Sieve ◽  
Natural Gas Desulfurization ◽  
Kinetic Selectivity

The equilibrium adsorption of H2S is substantially stronger than that of CH4 on carbons, including carbon molecular sieve (CMS). A carbon molecular sieve with a proper pore structure can provide a kinetic selectivity for H2S over CH4, thus further enhancing the overall selectivity (equilibrium plus kinetic) for H2S and providing the basis of natural gas desulfurization by adsorption. Kinetic selectivity requires a unique pore structure due to the small difference in the molecular dimensions of H2S and CH4 (~0.2 Å). Equilibrium and diffusion rate data for CH4 and H2S at 25°C have been measured in three commercial carbon molecular sieves: Bergbau Forschung CMS, Takeda CMS 3A and Takeda CMS 5A. The pores are either too small (in the two former carbons) or too large (in CMS 5A) for H2S/CH4 separation. Alterations to the pore structure either by controlled oxidation or carbon deposition by pyrolysis have been studied. Optimal results were obtained by pyrolysis of propylene on CMS 5A under the following conditions: 0.05 atm, 700°C, 5 min, weight gain of 0.67%. The resulting carbon molecular sieve retained the high equilibrium adsorption capacities while yielding a diffusion time constant ratio for H2S/CH4 of 8.2. This carbon is suitable for natural gas desulfurization by adsorption processes such as pressure swing adsorption. Temperature was the most important variable in pore structure alteration by carbon deposition. Under the optimal pyrolysis conditions, carbon was only deposited near the pore entrances.

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